464 



THE CANADIAN NATURALIST. 



[Dec. 



in spring coating damp walls and banks, and long mistaken ior 

 species of algae (figs. 1, 2, 3). From various cells of this, young 



Fig. 1. Spore ot 

 Fun aria hygrometrica. 



Fig. 2. Spore of Fanaria hygrometrica 

 germinating. 



Fig. 3. Prothallium and young plant. 

 plants are developed, whose fine radicles penetrate the soil ; their 

 leaves shoot up, and they become like the parent from which the 

 spore emanated; and being now capable of maintaining an inde- 

 pendent existence, the prothallium, no longer needed, dies away, 

 except in a few minute annual mosses of delicate texture, where 

 it is persistent during their whole life. But some mosses rarely 

 produce fruit ; yet it is necessary that their reproduction should 

 be ensured, and we find prothallium also developed from tubercles 

 on the roots, from gemmae or buds occurring on the leaves, or 

 even from the cell-tissue of leaves themselves ; while in some 

 mosses a portion of the leaves become altered into gemmae, and 

 clustered in a head on the top of a naked stalk called a pseudopo- 

 dium, as in Tetrapliis pellucida and in Aulacomnium (fig. 4). 



Fig. 4. Pseudopodium of Aulacomnium androgynum, 

 with one of the gemma. 



The roots. — These are slender fibrils, by which the plants are 



